• 공업화학
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• 제2권3호
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• pp.193-198
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• 1991

후막 구리도체는 귀금속계 도체에 비하여 가격이 저렴하고 전기전도도, 납땜성, 땜납 침식저항, 와이어 본딩성등의 양호한 성질 때문에 매우 중요성을 갖는다. 그러나 우수한 후막 구리도체를 형성하는 것은 구리가 높은 온도에서 쉽게 산화하는 성질로 인해 상당히 복잡하다. 양호한 구리후막을 얻기 위하여 하이브리드 마이크로회로업계는 질소분위기, 반응성분위기 또는 공기분위기를 사용한다. 이 글에서는 후막 구리도체의 소성공정과 세종류의 소성분위기에 대하여 종합적으로 고찰하였다.

• 동굴
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• 제82호
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• pp.5-7
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• 2007

In this paper, p-n junction formation using screen-printed metalization and co-firing is used to fabricate high-efficiency solar cells on single- crystalline silicon substrates. In order to form high-quality contacts, co-firing of a screen-printed Ag grid on the front and Al on the back surface field is implemented. These contacts require low contact resistance, high conductivity, and good adhesion to achieve high efficiency. Before co-firing, a statistically designed experiment is conducted. After the experiment, a neural network (NN) trained by the error back-propagation algorithm is employed to model the crucial relationships between several input factors and solar cell efficiency. The trained NN model is also used to optimize the beltline furnace process through genetic algorithms.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권4호
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• pp.152-154
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• 2005

We demonstrate a simple $CO_2$ laser by controlling firing angle of a TRIAC switch in ac power line. The power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of TRIAC gate is varied from $45^{circ}$ to $135^{circ}$. A ZCS(Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of the TRIAC precisely. The maximum laser output of 40W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60Hz, and a TRAIC gate firing angle of $90^{circ}$.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.109-110
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• 2013

The purpose of this study was to investigate pozzolanic activity according to the firing temperature of the rice straw ash. In order to measure amount of SiO2 of rice straw ash, XRF(X-ray fluorescence) analysis was tested. Also to evaluate properties of mortars using rice straw ash, mortar flow, cement setting time, compressive strength was tested. As a results, as the mortar with a mixture ratio of rice straw ash up to 15% was found to have a compressive strength superior to that of plain mortar.

• 한국국방경영분석학회지
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• 제2권1호
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• pp.163-176
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• 1976

The artillery fire is characterized by great damage that can be inflicted simultaneously to an area through concentrated firing. The field artillery guns used in R.O.K. Army are generally old. Thus high values of their velocity errors cause wide dispersion of shell landings. Therefore effects of the concentrated firing is lessened. In this paper a general model which considers all error factors involved in firing in general, is established first. Then from this a basic model which includes the errors involved in concentrated firing only, such as the ballistic error, velocity error, target density function, and damage function, is extracted. Among many weapon systems now in use a specific one called gun 'A' is selected and its concentration effects are measured through computer simulation. The results show that as the velocity error of a battery increases, its target coverage capability, i. e. concentration effect, decreases. Therefore the need arises for the field artillery commander to know beforehand characteristics, i.e. velocity errors, of the guns in his unit and also to carefully examine the problem of battery arrangement with the gun characteristics in mind in order to maximize the damage effects of his artillery unit.

• 한국세라믹학회지
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• 제55권2호
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• pp.116-125
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• 2018

Color shade variation was investigated in zirconia dental blocks, prepared using commercial powders. As a reference color-shade block we used the color indexes of A2, A3.5, A4 and B3, according to the VITA classical color scale. The zirconia powders for color shade blocks showed colors of white, yellow, pink and grey, respectively, after firing at $1530^{\circ}C$. The zirconia powders were mixed according to the recipe of color shade blocks and shaped at lower pressure using a uniaxial hydrostatic press. The shaped sample was inserted into a vinyl pack and sealed in a vacuum form machine. The shaped block samples were reshaped at 450 bar using an isostatic cold press and fired at $1530^{\circ}C$ for three hours. In order to investigate the atmospheric color variation with firing temperature, the A2, A3.5, A4 and B3 sintered blocks were fired between $700^{\circ}C$ and $1300^{\circ}C$ under controlled atmosphere of $pN_2$ and $pO_2$. The surface color picture was taken using a smart phone camera and compared with the results obtained using the VITA classical color scale. Quantitative color index value, CIELAB, was measured using a color-meter. Above $800^{\circ}C$, the color darkness greatly increased with the increase of the reduction temperature and keeping time.

• 대한안전경영과학회지
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• 제7권4호
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• pp.229-248
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• 2005

The purpose of this study is to identify the best firing condition for Celadon, which is one of the famous traditional pottery to represent Korean culture, by minimizing energy consumption, cutting firing time, shortening the time of processing ceramic making, in order to, save energy as well as to protect the potters' health. Most Korean potter starts their reduction from $950^{\circ}C$ to change kiln atmosphere. However on this study, reduction have started from $950^{\circ}C\;to\;1200^{\circ}C$ by increasing $50^{\circ}C$ at a time. Then the results are analyzed to be compared to previous Celadon, in colors, chroma, and brightness. As a results, it is found, that the best temperature for starting reduction is $1100^{\circ}C$, when chroma and brightness values to meet same with previous celadon. Therefore the best condition could be made by starting the reduction on $1100^{\circ}C$ to fire celadon, which would have shorten 2 hours of firing process and, at the same time, it could have saved the energy by 12%.

• 한국추진공학회지
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• 제4권3호
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• pp.19-28
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• 2000

고체추진 로켓모타의 개발이나 성능평가 때에는 추진기관의 추력, 연소실 압력, 온도, 연소시간 등 정적연소시험을 통해서 필요한 데이터론 측정한다. 그러나 휴대용 대공 유도무기의 경우에는 추진기 관의 화염으로부터 사수를 보호하기 위해 대단히 까다로운 안전규정을 요구하고 있다. 이러한 안전 규정들을 만족시키기 위해 설계된 분리장치나 점화안전장치의 개발 및 성능평가를 위해서는 이들 장치들이 결합된 추진기관에 대해 실제 비행 환경 하에서 설계목표의 신뢰도를 시험하기 위한 동적연소시험이 수행되어야 한다. 본 연구에서는 이러한 휴대용 대공 유도무기 추진시스템의 개발이나 성능평가를 위한 동적연소시험 기법 및 동적시험대의 설계 및 제작에 관한 연구를 수행하였다.

• 대한치과기공학회지
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• 제35권4호
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• pp.353-358
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• 2013

Purpose: This study was observation shear bonding strength by compositional change and firing step of a Ni-Cr alloy for porcelain fused metal crown. The aim of study was to suggest the material for firing step of Ni71-Cr14 alloy to development of alloy for porcelain fused to metal crown. Methods: The test was on the two kinds of Ni-Cr alloy specimens. The surfaces of two alloys were analyzed by EDX in order to observe oxide characteristic. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{71}Cr_{14}$ alloy measured 23.32wt%, and $Ni_{59}Cr_{24}$ alloy was measured 23.03wt%. And the maximum shear bonding strength was measured 58.02MPa between $Ni_{59}Cr_{24}$ alloy and vintage halo(H4 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shear bonding strength showed the highest bonding strength in H4 specimens.

• 한국군사과학기술학회지
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• 제11권4호
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• pp.13-19
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• 2008

In order to reduce the level of recoil force, new recoil technology must be employed. The present study discusses a soft-recoil system that can reduce dramatically the recoil force. The firing sequence of the soft recoil system is radically different from that of a conventional system. The gun is latched and preloaded in its out-of-battery position prior to firing. When unlatched, the gun is accelerated and forward momentum is imparted to the recoiling parts. This momentum is opposed by the ballistic force imparted by firing and the recoil force and stoke will be reduced. In the present study, the soft-recoil system with hydraulic dampers is simulated and its characteristics are investigated theoretically. The results of the simulation show that the soft-recoil system could dramatically reduce the recoil force and the recoil stroke compared to the conventional recoil systems. However, the soft-recoil system was not able to perform well when the firing fault modes like prefire, hang-fire, and misfire happen. Hence, we need to employ a control algorithm to prevent the damage of the recoil system due to these fault mode.